Two self-driving truck companies have told regulators their technology for warning motorists of a truck stopped on the side of the highway is safe enough to replace traditional reflective signs and road flares.

Waymo LLC and Aurora Operations Inc. have asked the Federal Motor Carrier Safety Administration to exempt for five years their highly automated (Level 4 and Level 5) trucks from regulations requiring such roadside warning devices. If FMCSA approves the exemption, the companies would be allowed to use cab-mounted beacons instead.

“Waymo and Aurora believe it is possible to achieve the safety purpose of the warning device in an alternative way by using forward- and rearward-facing amber flashing lights mounted on the cab at a height above the upper edge of the sideview mirrors,” FMCSA stated in a notice to be posted in the Federal Register on Friday.